* {
  padding: 0;
  margin: 0;
}
/* 两栏布局*/
.css1 {
  width: 100vw;
  height: 300px;
  background-color: pink;
  display: flex;
}
.css1_box_left {
  width: 200px;
  height: 100%;
  background-color: skyblue;
}
.css1_box_right {
  flex: 1;
}

/* 三栏布局*/
.css2 {
  width: 100vw;
  height: 300px;
  background-color: pink;
  display: flex;
}

.css2_box_left {
  width: 100px;
  background-color: skyblue;
}
.css2_box_content {
  width: 100px;
  flex: 1;
  background-color: salmon;
}

.css2_box_right {
  width: 200px;
  background-color: skyblue;
}

.css3 {
  width: 100vw;
  height: 100vh;
  display: flex;
  background-color: pink;
  justify-content: center;
  align-items: center;
}
.css3_box {
  width: 400px;
  height: 400px;
  background-color: skyblue;
}
